1. Field of the Invention
The present invention relates to a magnetic reproducing apparatus for reproducing a magnetic signal recorded on a magnetic recording medium by using a magneto-resistance effect type magnetic head element and to a method for detecting wear of the magneto-resistance effect type magnetic head element.
2. Description of the Related Art
Hitherto, a magnetic induction type magnetic head element such as a so-called metal-in-gap type magnetic head element and a laminate type magnetic head element has been used as a magnetic head element in a reproducing apparatus for reproducing magnetic signals to/from a magnetic tape such as a video tape recorder (VTR) and a data recorder unit used for backing up data.
In the above-mentioned reproducing apparatus, however, application of a magnetic head element which allows a reproduced output to be obtained fully from narrower tracks has been required to be able to deal with the advancement of digitalization and multi-media of the future.
In order to meet with such requirement, there has been proposed a technology of using a magneto-resistance effect type magnetic head element (hereinafter referred to as an MR head) using a magneto-resistance effect used as a reproducing magnetic head element in a hard disk unit and the like as a reproducing magnetic head element of the above-mentioned reproducing apparatus.
The MR head used in the hard disk unit and the like is created by bonding a pair of substrates made of soft magnetic substance for example in a body via a gap and by forming a thin film of a magneto-resistance effect element (hereinafter referred to as an MR element) which exhibits the magneto-resistance effect within the gap.
This MR head is drawing attention as a device essential for realizing the further high density magnetic recording because it readily permits narrower tracks because the width of the track is determined by the width of the MR element formed as a thin film, and because its reproducing sensitivity is high since the MR element is exposed out of a plane facing the magnetic recording medium.
By the way, the magnetic induction type magnetic head element used in the reproducing apparatus for reproducing magnetic signals to/from the magnetic tape in the past has permitted a certain degree of wear. However, because the MR element that exhibits the magneto-resistance effect is exposed out of the plane facing to the magnetic recording medium in the MR head, the restriction on its wear is strict as compared to that of the magnetic induction type magnetic head element.
Although the wear of the MR head has not been much of a problem because it reads the magnetic signal while floating on the magnetic disk in the hard disk unit, the wear of the MR head advances when it is used for a long period of time as it slides against the magnetic tape when the MR head is applied as the reproducing magnetic head element of the reproducing apparatus for reproducing the magnetic signal to/from the magnetic tape, because the reproducing apparatus reproduces the magnetic signal while sliding the magnetic head element against the magnetic tape.
The magnetic signal cannot be read adequately when the magnetic signal is to be read continuously by using the worn out MR head. Accordingly, it is necessary to detect the degree of wear caused by the use of the MR head and to replace the worn out MR head with a new MR head when the degree of wear of the MR head exceeds a predetermined value when the MR head is used as the reproducing magnetic head element of the reproducing apparatus for reproducing the magnetic signal to/from the magnetic tape.
The present invention has been devised in view of the above-mentioned circumstances and provides a magnetic reproducing apparatus which can detect the degree of wear of the magneto-resistance effect type magnetic head element for reading a magnetic signal adequately with a simple structure and a method for detecting the degree of wear of the magnetic head element.
An inventive magnetic reproducing apparatus comprises a magneto-resistance effect type magnetic head element for reading a magnetic signal recorded on a magnetic recording medium and wear detecting means for detecting the degree of wear of the magnetic head element from a value of resistance of the magnetic head element.
The magnetic signal recorded on the magnetic recording medium is read out of the magnetic recording medium by the magneto-resistance effect type magnetic head element in the inventive magnetic reproducing apparatus. The magnetic head element wears along the operation for reading the magnetic signal. The wear detecting means detects the degree of wear of the magnetic head element. The wear detecting means detects the degree of wear of the magnetic head element from the value of resistance of the magnetic head element.
Because the wear detecting means detects the degree of wear of the magnetic head element from the value of resistance of the magneto-resistance effect type magnetic head element in the inventive magnetic reproducing apparatus as described above, the degree of wear of the magnetic head element may be detected simply and adequately.
Preferably, the inventive magnetic reproducing apparatus further comprises alarm generating means for generating an alarm informing of the life of the magnetic head element when a value indicative of the degree of wear of the magnetic head element detected by the wear detecting means exceeds a predetermined value.
The inventive magnetic reproducing apparatus is provided with the alarm generating means which generates an alarm informing of the life of the magnetic head element when the value indicative of the degree of wear of the magnetic head element detected by the wear detecting means exceeds the predetermined value as described above, so that it can inform of the life of the magnetic head element to the user reliably.
Preferably, in the inventive magnetic reproducing apparatus, the wear detecting means measures the value of resistance of the magnetic head element when the magnetic head element is not operative to read the magnetic signal recorded on the magnetic recording medium and the degree of wear of the magnetic head element is detected based on this value of resistance.
It is also possible to detect the degree of wear of the magnetic head element adequately in the inventive magnetic reproducing apparatus without affecting the magnetic signal read out of the magnetic recording medium by the magnetic head element by measuring the value of resistance of the magnetic head element by the wear detecting means during when the magnetic head element is not operative to read the magnetic signal recorded on the magnetic recording medium and by detecting the degree of wear of the magnetic head element based on the value of resistance.
An inventive method for detecting a degree of wear of a magnetic head element comprises steps of measuring a value of resistance of a magneto-resistance effect type magnetic head element for reading a magnetic signal recorded on a magnetic recording medium and of detecting the degree of wear of the magnetic head element based on the value of resistance of the magnetic head element.
Because the inventive method for detecting the degree of wear of the magnetic head element comprises the steps of measuring the value of resistance of the magneto-resistance effect type magnetic head element and of detecting the degree of wear of the magnetic head element based on the value of resistance, the degree of wear of the magnetic head element may be detected simply and adequately.
Preferably, the method for detecting a degree of wear of a magnetic head element further comprises a step of generating an alarm informing of the life of the magnetic head element when the degree of wear of the magnetic head element exceeds a predetermined value.
Because the method for detecting the degree of wear of the magnetic head element comprises the step of generating an alarm informing of the life of the magnetic head element when the degree of wear of the magnetic head element exceeds the predetermined value as described above, it can inform of the life of the magnetic head element to the user reliably.
In the method for detecting the degree of wear of the magnetic head element, preferably the value of resistance of the magnetic head element is measured when no operation of reading the magnetic signal recorded on the magnetic recording medium is carried out.
It is then possible to detect the degree of wear of the magnetic head element adequately by the inventive method for detecting the degree of wear of the magnetic head element without affecting the magnetic signal read out of the magnetic recording medium by the magnetic head element by detecting the degree of wear of the magnetic head element during when the magnetic head element is not operative to read the magnetic signal recorded on the magnetic recording medium.
The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawings.